The present invention relates to a method and apparatus for providing user-directed control of a virtual-environment manipulator, and particularly, but not exclusively, where such a manipulator is controlled to follow, at least partially, the movements of a users limb and reproduce such movements within a virtual environment.
The form taken by the virtual environment will depend on the intended use of the system and may, for example, comprise the interior of a building for an architectural modelling application, or urban or surreal landscapes for games or other applications, around which environment a virtual manipulator controlled by the user is moved. The modelled form of the virtual manipulator may vary as required by the application (along with the form of the virtual objects to be manipulated), from simulacra of human hands or animal claws, through other biological grasping devices (such as the tentacles or suction pads of an octopus) to mechanical equivalents and specialised tools. Whatever the particular form, the manipulator must be able (under direct or indirect user control) to hold an object (such that it may be moved or stopped from movement by the manipulator), it must be able to release an object once held, and it must be able to impart motion to an object (pushing) without having first to hold it. In the following, the term "virtual environment" will be used for all such computer-generated virtual landscapes or situations: the term "physical environment" will be used to denote the `real-world` surroundings of the user, for example a room in which the user contacts the various hardware devices, such as a head-mounted display (HMD), which provide the interface to the virtual environment. The terms "virtual body" and "physical body" should be construed accordingly.
One example of a virtual manipulator controlled through a haptic glove is described in International Patent Application WO92/18925 (W. Industries). Within the virtual environment (viewed for example via HMD) the users hand appears as a cursor, which undergoes changes corresponding with movement and flexure of the users hand, by means of which cursor the user interacts with the objects by "picking them up" or "moving them about". A similar three-dimensional cursor, again directed via a glove with mounted flexure sensors, is described in European patent application EP-A-0 211 984 (Lanier et al).
A problem with these systems is their intent to accurately monitor and reproduce the motions of a users hand (along with added features such as the tactile feedback of WO 92/18925) which greatly increases the processing capacity required. This processing requirement may be lessened if short cuts are taken with, for example, the generation of the virtual environment, but this may be counter-productive in actually reducing the users sense of immersion.
It is therefore an object of the present invention to provide a means for manipulation of virtual objects modelled in a three-dimensional environment.
It is a further object to provide such means having lower processing requirements than has heretofore been the case.